1. Field of the Invention
This invention concerns a table having a substantially flat surface having means for causing flat plates of glass to be severed along substantially straight lines.
2. Description of the Prior Art
In the cutting of large pieces of plate glass into pieces of smaller size, a table is employed generally having a horizontally disposed flat working surface. The working surface may be covered with a soft pile carpet and may also be equipped with a glass sheet flotation system wherein pressurized air directed upwardly against the glass enables the sheet to be easily manipulated.
The cutting or breaking of the glass sheet is generally accomplished by first scoring the upper surface of the sheet along a straight line with a hardened scribing tool, then positioning the scored line above fulcrum means such as a breaker bar caused to rise up from the surface of the table. Downward force is then applied upon the extremity of the glass sheet somewhat elevated above the table by virtue of the lifting effect of the breaker bar. Such downward force, which may be applied by an operator or by the weight of the glass, causes the sheet to crack or break along the scored line.
The generally employed breaker bars are usually configured to reside within slots recessed into the working surface. By means of a system of levers, the operator can cause the breaker bars to rise out of their slots to their operational position. However, maintaining the bars in their upwardly deployed functional state requires a reliable locking mechanism.
It is found that, in the course of time and long use, mechanical components that deploy and secure breaking bars become unreliable, or necessitate extra operator time. There is also poor mechanical durability and reliability in tables having a first array of parallel breaker bars and an orthogonally crossing second array of parallel breaker bars. In attempts to reduce inadvertent glass breakage by metal breaker bars, softer breaker bar materials have been tried but result in further problems of durability.
U.S. Pat. No. 3,668,955 to Rupprecht et. al. discloses a glass-breaking table having recessed grooves containing a plurality of hydraulic piston-cylinder assemblies 97 that push breaking bars 91 upwardly into contact with the overlying scored glass plate. Such apparatus for the cutting or breaking of glass plate is of expensive, complex construction, and is subject to failure when any of the multitude of cylinders malfunction.
U.S. Pat. No. 4,946,086 to Suuronen et. al. concerns apparatus for tearing continuous form perforated paper, such as computer-generated paper. The apparatus employs clamping means interactive with an anvil surface to grip the paper. A tensioning hose whose cross-sectional configuration is laterally extended, is contained within a recess in the anvil surface. When inflated, the hose contacts the paper at laterally spaced sites spanning a perforation line to produce a tensioning or stretching effect that tears the paper at the perforation line.
It is accordingly a primary object of the present invention to provide a glass cutter's table for achieving accurate breaking of plate glass along scored straight lines.
It is another object of this invention to provide a glass cutter's table as in the foregoing object having a plurality of fulcrum means controllably deployable from beneath the surface of said table.
It is a further object of the present invention to provide a glass cutter's table of the aforesaid nature having two parallel arrays of fulcrum means in orthogonally intersecting relationship.
It is a still further object of this invention to provide a glass cutter's table of the aforesaid nature which is easy to use, reliable, durable and amenable to low cost manufacture.
These objects and other objects and advantages of the invention will be apparent from the following description.